Polyhydroxyalkanoates (PHAs) are a class of polyester polymers of microbial origins and considered biodegradable alternatives to conventional plastics. To make PHAs cost-competitive to synthetic plastics, its production cost including that for extraction should be significantly reduced. Herein, this study aimed to develop an effective extraction method based on combined mechanical disruption and chemical digestion for recovery of high-purity medium-chain length PHAs (mcl-PHAs) with lower cost. mcl-PHAs were first synthesized by Pseudomonas strains using different substrates including waste cooking oil, oleic acid, and whey-derived acid stream. High pressure homogenization (HPH) coupled with surfactant treatment and further mild alkaline hydrogen peroxide oxidation were found to have strong synergy for PHA recovery. The optimized condition resulted in near 90% mcl-PHA recovery with more than 93% purity. The harsh treatment condition led to partial depolymerization of PHAs. The characterization of extracted high-purity PHAs for chemical, thermal, and mechanical properties revealed market-desired attributes for downstream applications.
